Improve link checking

Closes #484

See merge request !1044

Update compendium on MobaXterm

See merge request !1042

Merge branch 'dead-external-link' of gitlab.hrz.tu-chemnitz.de:zih/hpcsupport/hpc-compendium into dead-external-link

- Normal CI/CD pipelines: Only check internal links
- Add switch to link-checker script to check internal and external links
  - Will be invoked via schedule once a week

Link checker is enabled via ENABLED_HTMLPROOFER=true by the check-links
script

- Dockerfile: Update html-proofer-plugin from version 0.8.0 to current 1.2.1
  - The new version provides functionality, we want, e.g., specification of "ignore_urls"
- mkdocs.yaml: Adjust settings for html-proofer-plugin
  - raise error after all urls have been checked
  - specifiy urls to be ignored
  - enable validation of external urls

Automated merge from preview to main

See merge request !1038

Main

See merge request !1037

Fix link to `Contribution guide`

See merge request !1036

Improve readability of fingerprints by using monospace

See merge request !1035

Add instruction how to show fingerprint without login.

Fix typo slurm_examples.md

See merge request !1033

Automated merge from preview to main

See merge request !1032

Add information on CUDA modules to GPU page

Closes #573

See merge request !1031

Fix link to module environments

See merge request !1030